cosmopolitan/libc/dns/lookupservicesbyname.c
Justine Tunney ff77f2a6af
Make improvements
- This change fixes a bug that allowed unbuffered printf() output (to
  streams like stderr) to be truncated. This regression was introduced
  some time between now and the last release.

- POSIX specifies all functions as thread safe by default. This change
  works towards cleaning up our use of the @threadsafe / @threadunsafe
  documentation annotations to reflect that. The goal is (1) to use
  @threadunsafe to document functions which POSIX say needn't be thread
  safe, and (2) use @threadsafe to document functions that we chose to
  implement as thread safe even though POSIX didn't mandate it.

- Tidy up the clock_gettime() implementation. We're now trying out a
  cleaner approach to system call support that aims to maintain the
  Linux errno convention as long as possible. This also fixes bugs that
  existed previously, where the vDSO errno wasn't being translated
  properly. The gettimeofday() system call is now a wrapper for
  clock_gettime(), which reduces bloat in apps that use both.

- The recently-introduced improvements to the execute bit on Windows has
  had bugs fixed. access(X_OK) on a directory on Windows now succeeds.
  fstat() will now perform the MZ/#! ReadFile() operation correctly.

- Windows.h is no longer included in libc/isystem/, because it confused
  PCRE's build system into thinking Cosmopolitan is a WIN32 platform.
  Cosmo's Windows.h polyfill was never even really that good, since it
  only defines a subset of the subset of WIN32 APIs that Cosmo defines.

- The setlongerjmp() / longerjmp() APIs are removed. While they're nice
  APIs that are superior to the standardized setjmp / longjmp functions,
  they weren't superior enough to not be dead code in the monorepo. If
  you use these APIs, please file an issue and they'll be restored.

- The .com appending magic has now been removed from APE Loader.
2023-10-03 06:17:16 -07:00

107 lines
5 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ This is free and unencumbered software released into the public domain. │
│ │
│ Anyone is free to copy, modify, publish, use, compile, sell, or │
│ distribute this software, either in source code form or as a compiled │
│ binary, for any purpose, commercial or non-commercial, and by any │
│ means. │
│ │
│ In jurisdictions that recognize copyright laws, the author or authors │
│ of this software dedicate any and all copyright interest in the │
│ software to the public domain. We make this dedication for the benefit │
│ of the public at large and to the detriment of our heirs and │
│ successors. We intend this dedication to be an overt act of │
│ relinquishment in perpetuity of all present and future rights to this │
│ software under copyright law. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, │
│ EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF │
│ MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. │
│ IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR │
│ OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, │
│ ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR │
│ OTHER DEALINGS IN THE SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/dce.h"
#include "libc/dns/servicestxt.h"
#include "libc/errno.h"
#include "libc/fmt/conv.h"
#include "libc/intrin/safemacros.internal.h"
#include "libc/macros.internal.h"
#include "libc/mem/mem.h"
#include "libc/str/str.h"
/**
* Opens and searches /etc/services to find port for a given name.
*
* @param servname is a NULL-terminated string
* @param servproto is a NULL-terminated string (eg "tcp", "udp")
* (if servproto is an empty string,
* if is filled with the first matching
* protocol)
* @param servprotolen the size of servproto
* @param buf is a buffer to store the official name of the service
* (if NULL, the official name is not stored)
* @param bufsize is the size of buf
* @param path is the location of services file
* (if NULL, uses /etc/services)
* @return -1 on error, or positive port number
* @note aliases are read from file for comparison, but not returned.
* @see LookupServicesByPort
*/
int LookupServicesByName(const char *servname, char *servproto,
size_t servprotolen, char *buf, size_t bufsize,
const char *path) {
FILE *f;
char *line;
size_t linesize;
char pathbuf[256];
int found, result;
char *name, *port, *proto, *alias, *comment, *tok;
if (servprotolen == 0 ||
!(f = fopen(path ? path : GetServicesTxtPath(pathbuf, sizeof(pathbuf)),
"r"))) {
return -1;
}
line = NULL;
linesize = 0;
found = 0;
result = -1;
if (bufsize) strcpy(buf, "");
while (found == 0 && (getline(&line, &linesize, f)) != -1) {
if ((comment = strchr(line, '#'))) *comment = '\0';
name = strtok_r(line, " \t\r\n\v", &tok);
port = strtok_r(NULL, "/ \t\r\n\v", &tok);
proto = strtok_r(NULL, " \t\r\n\v", &tok);
if (name && port && proto) {
alias = name;
while (alias && strcasecmp(alias, servname) != 0)
alias = strtok_r(NULL, " \t\r\n\v", &tok);
if (alias) /* alias matched with servname */
{
if (!servproto[0] || strncasecmp(proto, servproto, servprotolen) == 0) {
if (!servproto[0] && !memccpy(servproto, proto, '\0', servprotolen)) {
strcpy(servproto, "");
break;
}
if (bufsize && !memccpy(buf, name, '\0', bufsize)) {
*buf = 0;
break;
}
result = atoi(port);
found = 1;
}
}
}
}
free(line);
if (ferror(f)) {
errno = ferror(f);
return -1;
}
fclose(f);
if (!found) return -1;
return result;
}